Pattern forming method

ABSTRACT

A method of forming any film pattern on an arbitrary substrate, more particularly, a pattern forming method which comprises selectively forming a film on an arbitrary substrate, by use of chemical reaction, and further, a method of forming a pattern of an organic film by selectively removing the organic film at a lower layer, with the pattern of the Langmuir-Blodgett&#39;s film containing Si as a mask.

This application is a division of Ser. No. 030,612 filed Mar. 27, 1987,now U.S. Pat. No. 4,829,766 which is a continuation of Ser. No. 751,256filed Jul. 2, 1985, now U.S. Pat. No. 4,751,171.

BACKGROUND OF THE INVENTION

The present invention relates to a pattern forming method which can beused in manufacture of semiconductor elements, printing plates etc., andparticularly relates to a pattern forming method for selectively forminga film on an arbitrary substrate by use of chemical reactions.

Heretofore, resist patterns in the manufacture of semiconductor elementsor resin patterns which provide negative plates in the manufacture ofprinting plates have been manufactured in the following manner: A resinfilm which may be polymerized or decomposed by irradiation of light isformed on the substrate and, then light beams are irradiated in anyarbitrary pattern on the resin film, followed by developement, therebyforming the pattern. More and more refining of these resist patterns hasbecome demanded for attainment of higher density of semiconductorelements and higher quality of printed forms.

Particularly, in the manufacture of very large scale intergrated circuit(VLSI), there has arisen the need for forming at a high accuracy aresist pattern in fine lines of submicron order. While this process islargely affected by the physical properties of the resist itself,generally, the finer the pattern it is desired to have (thus, forincreasing the resolution), the resist film applied needs to thinner. Onthe other hand, when it comes down to providing submicron patterns, wetetching can not be utilized, but such a dry etching as ion etching,plasma etching or sputter etching, etc., must be utilized. In order toimprove the dry etching resistance* of the resist pattern, generally,the resist coating needs to be thick.

Accordingly, in order to meet the above-stated two requirements, it isadvisable to develop a photoresist whose coating is thick, but giveshigh resolution, or a photoresist whose coating is thin but gives highdry-etching resistance. However, presently, there is available no suchmaterial.

On the other hand, heretofore, resist patterns usesd in manufacturingintegrated circuits (IC) are generally formed in the following manner:The photoresist is applied on a semiconductor substrate by use of arotary coating device using a spinner and the substrate is exposed in aspecified pattern, followed by development, thereby forming the resistpattern. Recently, to fill the need of fine pattern forming inmanufacturing VLSI, forming a resist pattern which is highly accurate inpattern dimensions and which moreover, has no pin-hole is desired.However, generally, when the method of applying the photoresist by therotary coating is used, if the semiconductor substrate which forms thebase has any stepped parts, the film thickness of the photoresistbecomes irregular, this the coating being thinner at the top of eachconvex part, but thicker at the bottom of each concave part. Therefore,even if the exposure is made with a photo-mask having an equal linewidth, the line widths of the pattern differ between that at the top ofthe convex part and that at the bottom of the concave part. Furthermore,to achieve the pattern of the order of 0.5-1 μm at a high accuracy as inmanufacturing VLSI, the thickness of the photoresist coating needs to bereduced. However, taking account of etching resistance and prevention ofpin-hole when applying the coating, the film thickness needs to belarger than a certain value and due to this coating thickness, there isa limitation in the forming of the fine pattern.

Further, as a method of forming thin film having no pin-hole, a formingmethod of very thin photoresist film using the Langmuir Blodgett'stechnique (hereinafter referred to as LB technique) is in the process ofdevelopment. However, by this method, the pattern can be obtained at ahigh accuracy, but since the coat thickness of one layer is on the orderof 20-30Å, normally about 100 layers need to be formed in order toresist the plasma etching in manufacturing IC.

SUMMARY OF THE INVENTION

It is the object of this invention to provide a method for forming apattern which has high resolution and excellent etching resistance.

This and other objects will be accomplished by a pattern forming methodwhich comprises a step of forming on a substrate a responsive filmcontaining responsive groups which undergo chemical reactions whenexposed to energy beams (electron beam, ion beam, light, X-ray, etc.), astep of selectively deactivating parts of the responsive groups byirradiating such energy beams in a pattern, and a step of bondingchemical reagent to the parts of the responsive film where theresponsive groups remains, thereby forming a resin film of an ultra-finepattern.

In a specific embodiment, as the chemical reagent, there are employedmolecules having at one end thereof groups which are adapted to reactwith the responsive groups or such responsive groups which are modifiedand having at the other end thereof responsive groups which perform thesame action as the responsive group does. By repeating a plural numberof times the process of selectively bonding the chemical reagent, thethickness of the patterned resin film is increased or further, thedry-etching resistance is improved by having atoms high in thedry-etching resistance contained in the molecule to be bonded with theunderlying film.

Further, in another specific embodiment, used as the means for formingthe responsive film is the Langmuir Blodgett's technique or the chemicaladsorption method. By cumulatively forming monomolecular film layers insuch a way that the energy beams responding groups are juxtaposed andlaid bare on the substrate surface, not only improvement in sensitivitybut the forming of ultra-fine pattern are made possible.

In still another embodiment, on the substrate, the above-describedpattern forming is performed, with an organic film interposedtherebetween and further, with this pattern as the mask, parts of theorganic film at the lower layer are etched away, thereby transferringthe pattern to the organic film. Used as the chemical reagent, are chainsiloxane molecules having chlorine at both ends thereof. Using asubstrate whose surface is hydrophilic and as the responsive film,straight chain hydrocarbons having vinyl or cyano group at one endthereof and chlorosilane group at the other end thereof, monomolecularresponsive film is formed on the substrate surface by chemicaladsorption reaction such that the responsive groups are juxtaposed andlaid bare on the substrate surface. The responsive film may be formed bythe LB technique, using straight chain hydrocarbons having such ahydrophilic group as silanol group, etc., in place of chlorosilanegroup. A step of turning the surface hydrophilic by way of plasmatreatment or coating or absorption, etc., of a surface active agent maybe included, when a substrate whose surface is hydrophobic is used. Aresponsive film is formed on an arbitrary substrate, interposed by anorganic film, siloxane molecules are selectively bonded to this filmand, thereafter, through oxygen plasma treatment, the pattern formed bysiloxane molecules is transferred to the organic film. A step ofsubstituting with hydroxyl group the chlorine at one end of eachremaining siloxane molecule after the bonding reaction and a step offurther subjecting straight chain siloxane molecules having chlorinebonded at both ends to a bonding reaction with the hydroxyl groups areperformed more than once.

Further the present invention relates to a pattern forming method on anarbitrary substrate characterisized by a step of forming a sensitive LBfilm containing Si, with an organic film interposed therebetween, a stepof forming a pattern of the LB film by selectively polymerizing ordecomposing the sensitive LB film by irradiation of energy beams,followed by development, and a step of selectively etching the organicfilm by means of plasma containing oxygen, with the pattern of the LBfilm as the mask.

More particularly, on the substrate surface to be subjected to etchingprocess, preliminarily, any sharp stepped parts are eliminated, anorganic film is formed to a thickness of the order usable as the etchingresist and futher, on top of it, several layers of sensitive LB filmcontaining Si are formed by the LB technique. Thereafter, the LB film isselectively exposed to light, electron beam, ion beam, X-ray, etc.,followed by development, thereby first forming the pattern of LB filmand with this LB film pattern as the mask, the organic film at the lowerlayer is selectively etched, thereby forming the etching resist patternfor forming the base.

This invention has various advantages, among which is its capability offorming the pattern at a high resolution and with excellent etchingresistance.

While the novel features of the invention are set forth withparticularity in the appended claims, the invention, both as to itsorganization and content, will be better understood and appreciated,along with other objects and features thereof from the followingdetailed description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 (a)-(h) are sectional views showing the steps of a firstembodiment for explanation of the method of this invention, (a), (c),(e) and (g) of this figure respresenting conceptual views of section ofthe substrate in the successive steps, and (b), (d), (f) and (h) of thisfigure expanded views at the molecular scale level of the parts A-Dindicated in (a), (c) (e) and (g), respectively;

FIGS. 2 (a)-(c) are sectional views showing the steps of the secondembodiment of this invention, conceptual diagrams for explanation of thesteps of transferring the pattern to the organic film, following theprocess of a first embodiment;

FIGS. 3 (a)-(h) are sectional views showing the steps of the patternforming method of a third embodiment, (a), (c), (e) and (g) of thisfigure being sectional views of the substrate, and (b), (d); (f) and (h)respectively expanded views of parts A, B, C and D indicated in (a),(c), (e) and (g);

FIGS. 4 (a), (b), and (c) are sectional views showing the steps of thepattern forming method of a fourth embodiment of this invention;

FIGS. 5 (a)-(c) are sectional views showing the steps of the patternforming method of a fifth embodiment of this invention; and

FIG. 6 is a sectional view showing an expanded sectional view of thepart A in FIG. 5 and being a view for explanation of the structure ofthe LB film.

DETAILED DESCRIPTION OF THE INVENTION

In the following, embodiments of the pattern forming method of thisinvention are described with reference to FIGS. 1-6.

(EMBODIMENT)

A first embodiment of this invention is described with reference toFIG. 1. On a Si substrate 10 formed with SiO₂, there is formed bychemical adsorption process, a monomolecular film 12 of ##STR1## throughthe reaction with surface of silane surface active agent, e.g., CH₂═CH--(CH₂)_(n) --SiCl₃ (n represents an integer, preferably being10-25). For example, the treated substrate is dipped in a solution ofthis surfactant at its concentration of 2.0×10⁻³ -5.0×10⁻² mol/l in 80%n-hexane, 12% tetrachloromethane and 8% chloroform, to form a bonding 14of ##STR2## at the SiO₂ surface [FIG. 1 (a)].

Now, the vinly groups 16 of the silane surface active agent arejuxtaposed on the substrate surface forming a film [FIG. 1 (b)], andwill undergo polymerization reaction among surrounding vinly groupsunder irradiation by electron beams. Accordingly, electron beams 18 areirradiated onto the surface in a pattern, as shown in FIG. 1 (c). Then,as shown in FIG. 1 (d), the double bonds of the vinly groups at theparts 20 which are irradiated by electron beams are mutually combined tobe selectively deactivated.

Then this substrate is dipped in 1 mol/l THF solution of diborane andfurther immersed in an aqueous solution having 0.1 mol/l of NaOH and 30%H₂ O₂, thereby adding hydroxyl groups 22 to unirradiated vinyl groups[FIGS. 1 (e) and (f)].

Thereafter, further CH₂ ═CH---(CH₂)_(n) --SiCl₃ is set to react withhydroxyl groups 22 similarly as above described, thereby forming thebonding 24 of ##STR3## [FIG. 1 (h)]. Thus by this process, one layer ofthe molecule of ##STR4## 26 is selectively combined, yielding the filmpattern 28.

In the following, there is shown how an ultrafine pattern 28 of thenecessary thickness of about 30-300A of cumulated layers of silanesurface active agent is formed by repeating the step of adding hydroxylgroups 22 to the vinyl groups of the silane surface active agent 12formed in juxtaposed arrangement and the step of further adding anotherlayer of silane surface active agent 26.

It should be noted that while in the above described examples, asubstrate which forms ##STR5## bonding by reaction with --SiCl₃ of thesilane surface active agent, that is, a Si substrate 10, formed withSiO₂, is used as an example, besides it, such inorganic substances asAl₂ O₃, glass, etc., and such organic substances as polyvinyl alcohol,etc., are usable as the substrate.

When the substrate surface is coated with some other water repellentsubstance, hydrophilic groups are arranged side by side with each otheron the overall surface of the substrate by forming the LB film or themethod of turning the substrate surface hydrophilic by way of O₂ plasmatreatment, etc. Although the adhesive power is low in the LB film, evenif the substrate surface material is water repellent, by halting thecumulation at a layer where the water repellent surface is formed on thesubstrate side, it is possible to completely turn the surfacehydrophilic.

On the other hand, when the substrate is subjected to O₂ plasmatreatment, its surface is oxidized to be hydrophilic.

(EMBODIMENT 2)

For example, as shown in FIG. 2, on the substrate 10, an organic film,e.g., a rubber base resist layer 30, is applied and on this surface, alayer 32 subjected to O₂ plasma treatment (e.g., at 0.01 Torr and 100 Wfor about 30 sec) is formed; thereafter, silane surface active agent isabsorbed on the resist surface in the similar way as in the above-statedembodiment, thereby forming a monomolecular film 12 [FIG. 2 (a)].

Then the similar steps are repeated just as in Embodiment 1, therebyforming a pattern 28 made up of a surface active agent containing Si[FIG. 2 (b)]. Thereafter, this treated substrate is subjected to aplasma treatment in CF₄ gas with 10% O₂ added and with the pattern 28 asthe mask, whereby the sensitive film containing Si which has beendeactivated beforehand is selectively removed. Then the pattern 28 ofthe surface active agent may be transferred to the photoresist layer 30by etching the resist 30 with O₂ plasma, with the pattern of the surfaceactive agent containing Si as the mask [FIG. 2 (c)]. In this instance, arubber base resist layer was used as the organic film however, whatevermaterial which may be etched by O₂ plasma is obviously usable. Thepattern of the surface active agent containing Si which tends to formSiO₂ has the advantage of ensuring adequate etching resistance againstO₂ plasma without using substantially thick cumulative film layers. Onthe other hand, after the pattern has been transferred to thephotoresist layer, since the photoresist layer may be made adequatelythick, this pattern is utilizable as an ultra-fine resist pattern havingadequately large etching resistance against dry-etching (e.g., ionetching or sputter etching) which is generally employed in themanufacturing process of VLSI.

In the above two embodiments, a method of performing adsorbing reactionwith silicon surface active agent as the responsive film is illustrated,but if the reagent with its --Cl substituted with --OH beforehand (CH₂═CH--(CH₂)_(n) --Si (OH)₃, etc.) is used, the responsive film may beformed by the LB technique.

According to Embodiments 1 and 2, forming of ultra-fine pattern ispossible, since the energy beam responsive film is formed of single toseveral layer monomolecular cumulative film. Further, by conducting theselected film growing reaction through reaction between --SiCl₃ and --OHgroups, a pattern having large oxygen dry-etching resistance may beobtained. Accordingly, when the organic film is utilized as the lowerlayer, the pattern transfer to the organic film by oxygen dry-etching iseasy.

The LB technique and the adsorption method for use in forming theresponsive film, which permits the film formation to proceed throughintersurface reaction with the substrate surface, are not substantiallyaffected by stepped parts of the substrate and, therefore, they areenormous effects, when utilized for substrates involving many steppedparts as on VLSI elements.

In the Embodiments 1 and 2, intersurface reaction between --SiCl₃ and--OH is taken up as an example, but any other materials, if theyfunction with similar mechanism, are usable. Accordingly, the method ofthis invention is highly effective in improving the formation ofultra-fine pattern, especially, the photolithographic process in themanufacture of VLSI, etc.

The method of this invention will hereafter have applications as amolecular device manufacturing technique by utilizing reagentscontaining molecules which form π-conjugate polymers, for example, suchfunctional molecules as --C.tbd.C--C.tbd.C--, --C₆ H₄ --, --C₄ NH₃ --,--C₄ SH₂ --. --C₆ H₄ --CH═CH--, --C₆ H₄ --S--, --C₆ H₄ --O--, etc.,between straight chain CH₂ bonding inside the molecules of silanesurface active agents shown in the above-stated embodiments or as theirside chains.

(EMBODIMENT 3)

A third embodiment of this invention is described with reference to FIG.3.

Referring to (a) of this figure, on the Si substrate 10 formed withSiO₂, a silane surface active agent [for example, CH₂ ═CH--(CH₂)_(n)--SiCl₃ (n being any integer, from 10 to 20)] is set to react with thesurface of the substrate 10 by the chemical adsorption method, therebyforming a monomolecular film 12 of ##STR6## For example, this substrateis dipped in a solution of this agent at a concentration of from2.0×10⁻³ to 5.0×10⁻² mol/l in 80% n-hexane, 12% tetrachloromethane and8% chloroform, thereby forming a bonding 14 of ##STR7## on the SiO₂surface. Now, as shown in FIG. 3 (b), the vinyl groups 16 are juxtaposedon the substrate surface forming a film. Then, to take advantage of thepolymerization reaction between surrounding vinyl groups induced byirradiation of electron beams, the electron beams 18 are irradiated in apattern, as shown in FIG. 3 (c). Thereby the double bonds of the vinylgroups of the parts 20 which have been irradiated by the electron beamsare combined with each other, as shown in FIG. 3 (d), thus effectingselective deactivation.

Next, as shown in FIGS. 3 (e) and (f), the thus treated substrate isdipped at room temperature in 1 mol/l THF solution of diborane andfurther immerszed in an aqueous solution of 0.1 mol/l NaOH and 30% H₂O₂, thereby adding hydroxyl groups 22 to the unirradiated parts of vinylgroups.

Thereafter, as shown further in FIGS. 3 (g) and (h), chemicalsubstances, for example, straight chain siloxanes (hereinafter referredto as siloxane molecules) having chlorine bonded at both ends, asrepresented by ##STR8## (where n designates an integer), etc., may beused in forming the bonding of ##STR9## through reaction with hydroxylgroups 22 similarly as abovedescribed. Thus by this process, a filmpattern 36 is formed of siloxane molecules 34 selectively bonded inlayers with the substrate 10.

Thereafter, by repeating the step of hydrolyzing ##STR10## chlorosilanegroups) formed side by side with each other on the surface of thesubstrate, thereby converting them into ##STR11## (silanol groups), andthe step of adding the siloxane molecules thereto, siloxane moleculesproviding the necessary thickness are cumulated (to a thickness fromseveral tens Å to several hundreds Å) and formed in an ultra-finepattern.

It should be noted that in the Embodiment 3, a substrate whose surfaceis hydrophilic, as it tends to form the ##STR12## bonding by reactionwith --SiCl₃ of the surface active agent, or Si substrate formed withSiO₂ is taken up as an example, but other materials such as Al₂ O₃,glass or other inorganic substances and polyvinyl alcohol or otherorganic substances are utilizable. On the other hand, if the substratesurface is coated with other materials which show water repellency, itis possible to provide hydrophilic groups side by side with each otherall over the substrate surface by forming the LB film or to turn thesubstrate surface hydrophilic by way of O₂ plasma treatment, etc., or touse the method of coating or adsorbing some surface active agent on thesurface. Although the LB film is poor in adhesive power, even when thesubstrate surface material is water repellent, if the cumulation processis halted at a layer where the water repellent surface is brought to thesubstrate side, it is possible to turn the surface completelyhydrophilic.

When the substrate surface is subjected to the O₂ plasma treatment, itwill be oxidized to exhibit hydrophilic property. As energy beamresponsive groups, acetylene groups or cyano groups may be used otherthan said vinyl groups.

In contrast, a responsive film having energy beam responsive groups issubjected to pattern irradiation in a gas atmosphere, thereby partiallyconverting them into active groups which are reactive with siloxanemolecules to be introduced in the later process. For example, there isavailable a method of adding the siloxane molecules after activating theresponsive film in a pattern by directly adding hydroxyl groups to itsvinyl groups by way of irradiation of electron beams in the pattern inan atmosphere of O₂ gas or H₂ O gas.

(EMBODIMENT 4)

In the fourth embodiment, the method exercised in the third embodimentis applied on a substrate on which an organic film is formed and thepattern formed by the third embodiment is transferred to the organicfilm.

FIG. 4 shows this embodiment. As shown in (a) of this figure, an organicfilm, e.g., a rubber base resist 30, is applied on the substrate 10, ontop of which a layer 32 subjected to a plasma treatment (e.g., for 30sec at 0.01 Torr and 100 W) is formed and the silane surface activeagent is adsorbed on the resist surface by the same method as that ofthe third embodiment. Next, the similar process as that of the thirdembodiment is repeated, to produce the pattern 36 formed of the surfaceactive agent containing Si, as shown in FIG. 4 (b); thereafter, byetching O₂ plasma resists 30 and 32 with the pattern 36 of the surfaceactive agent containing Si as the mask, as shown in FIG. 4 (c), it ispossible to transfer the pattern of the surface active agent to thephotoresist. In this instance, as the organic film, a rubber base resistwas used, but any materials which are etchable by O₂ plasma are usable.The pattern of the surface active agent containing Si which formsSiO.sub. 2 under exposure to O₂ plasma is advantageous, since adequateetching resistance may be secured without making the cumulated film verythick. On the other hand, as the pattern is transferred to thephotoresist, which may be formed adequately thick, the photoresist maybe utilized as an ultra-fine resist pattern which shows adequate etchingresistance to dry-etching (e.g., ion etching or sputter etching) whichis generally employed in the manufacturing process of VLSI.

It should be noted that while in the third and fourth embodiments, as amethod of forming the responsive film, adsorption reaction of thesilicon surface active agent is illustrated, by using a reagent in which--Cl has been substituted by --OH group beforehand [CH₂ ═CH--(CH₂) _(n)--Si(OH)₃, etc.], a responsive film may be formed even by the LBtechnique.

Since according to the third and the fourth embodiments, the energy beamresponsive film is formed as a from single to several layermonomolecular cumulated film, forming of ultra-fine pattern is possible.Further by making the selective film growth by way of adding reaction ofsiloxane molecules, a pattern having large dry-etching resistance isobtained. Accordingly, when an organic film is utilized as the lowerlayer, the pattern transfer to the organic film by oxygen dry-etching iseasy.

With the LB technique and the chemical adsorption process which areutilized for forming the responsive film on the principle that theselective growth of the film is advanced by the inter-surface reactionwith the substrate surface, the stepped parts of the substrate are notsubstantially affected. Therefore, they have enormous effects, whenapplied to substrates involving many stepped parts as on VLSI elements.

It should be noted that although the third and fourth embodimentsillustrate intersurface reaction between --SiCl and --OH, any materialsare usable which work on the similar reaction mechanism. Accordingly,the method of this invention is effective in improving the formation ofultra-fine pattern, especially in the photolithographic process in themanufacture of VLSI, etc.

It should be further noted that the method of this invention may beapplied as a molecular device, manufacturing technique by utilizingreagents containing functional molecules, for example, molecules whichare adapted to form π-conjugate polymers of --C.tbd.C--C.tbd.C--, --C₆H₄ --, --C₄ NH₃ --, C₄ SH₂ --, --C₆ H₄ --CH═CH--, --C₆ H₄ --S--, --C₆ H₄--O--, etc., between straight chain CH₂ bonding inside the silanesurface active agent molecule shown in the above-stated embodiments oras its side chains.

(EMBODIMENT 5)

As shown in FIG. 5, an organic film 42 is coated on an arbitrarilyirregular surface of substrate 40 of a semiconductor, etc. At this time,it is only proper that the coating is thick enough to round the steepstepped parts of the base substrate and to resist the etching, whilebeing one on the base substrate; it is not always necessary to apply iton the substrate surface until it becomes flat. Nor does the organicfilm 42 need to be sensitive to light.

Then by the LB technique, several layers of sensitive LB film containingSi are formed and are, then, selectively polymerized or decomposed bymeans of energy beams 46 such as light, electron beam, iron beam, X-ray,etc., (FIG. 5a) followed by developement, thereby forming the LB filmpattern 48 containing Si (FIG. 5b). At this time, usable as the LB filmmaterials containing Si are such compounds as w-tricosenoic acid,diacetylene monocarboxylic acid, 2-hexadecenoic acid, α-octadecylacrylic acid and octadecyl metacrylate, etc., of which the straightchain carbons are partly substituted by Si's.

Then, by treating the treated substrate in a plasma containing oxygensuch as O₂ plasma, etc., with the LB film pattern 48 containing Si asthe mask, the organic film 42 is selectively etched, thereby forming anorganic film pattern 50 (FIG. 5c). It should be noted that at this time,since the LB film contains Si, its resistance to O₂ plasma etching islarge; that is, the surface of the LB film is turned into SiO₂ by theaction of the O₂ plasma, consequently providing passivity to oxygen; itis for this reason that only several layers of LB films will adequatelywithstand the O₂ plasma etching, when done through ther primer organicfilm 42. Besides, since the LB film is a laminate of monomolecular filmsin principle, its thickness will become uniform, even if there are someirregularities in the primer coating (FIG. 6), so that the pattern maybe formed uniform all over the surface and with a high accuracy. InFIG,. 6, 52 represents hydrophobic part of the LB film reagent, while 54indicates its hydrophilic part.

Thereafter, it is possible to subject the base substrate to etching,with this organic film pattern 50 as the etching resist. Although inthis embodiment, as the LB film, there is illustrated negative type or areagent which is polymerized by energy beam, to be sure, the sameeffects will be achieved with positive type.

This fifth embodiment is characterized by the process of forming thepattern in the sensitive LB film containing Si and, then, transferringthis LB film pattern to the organic film, using O₂ plasma, which permitsa great deal of cutback on the cycle of lamination, as compared with theresist of LB film only, leading to drastic improvement in productivity.Furthermore,even if there are some stepped parts on the base substrate,the film thickness may be always kept uniform, for high dimensionalaccuracy of the pattern and the number of pin-holes produced is verysmall. All such particular features of the LB film are usable, enablingthe resist pattern to be transferred to the organic film at a highaccuracy, for great effects in the manufacture of VLSI whereultra-refining is required.

While specific embodiments of the invention have been illustrated anddescribed herein, it is realized that modifications and changes willoccur to those skilled in the art. It is, therefore, to be understoodthat the appended claims are intended to cover all modifications andchanges as fall within the true spirit and scope of the invention.

What is claimed is:
 1. A pattern forming method comprising:a step offorming several layers of a sensitivee Langmuir-Blodgett film comprisinga straight chain hydrocarbon containing Si atoms and responsive groupsof acetylene, cyano or vinyl at one end of the hydrocarbon chain, on anarbitrary substrate covered with an organic film; a step of forming apattern of the Langmuir-Blodgett film by selectively polymerizing ordecomposing the sensitive Langmuir-Blodgett film by irradiation ofenergy beams, followed by development; and a step of selectively etchingsaid organic film with plasma containing oxygen, with the pattern ofsaid Langmuir-Blodgett film as a mask.